Close the blinds during sleep to protect your health
Even moderate light exposure during sleep harms heart health and
increases insulin resistance
Date:
March 14, 2022
Source:
Northwestern University
Summary:
Exposure to even moderate ambient lighting during nighttime sleep,
compared to sleeping in a dimly lit room, harms your cardiovascular
function during sleep and increases your insulin resistance the
following morning, reports a new study. Just a single night of
exposure to moderate room lighting during sleep can impair glucose
and cardiovascular regulation, which are risk factors for heart
disease, diabetes and metabolic syndrome.
FULL STORY ========================================================================== Close the blinds, draw the curtains and turn off all the lights before
bed.
Exposure to even moderate ambient lighting during nighttime sleep,
compared to sleeping in a dimly lit room, harms your cardiovascular
function during sleep and increases your insulin resistance the following morning, reports a new Northwestern Medicine study.
==========================================================================
"The results from this study demonstrate that just a single night of
exposure to moderate room lighting during sleep can impair glucose and cardiovascular regulation, which are risk factors for heart disease,
diabetes and metabolic syndrome," said senior study author Dr. Phyllis
Zee, chief of sleep medicine at Northwestern University Feinberg School
of Medicine and a Northwestern Medicine physician. "It's important for
people to avoid or minimize the amount of light exposure during sleep."
There is already evidence that light exposure during daytime increases
heart rate via activation of the sympathetic nervous system, which kicks
your heart into high gear and heightens alertness to meet the challenges
of the day.
"Our results indicate that a similar effect is also present when exposure
to light occurs during nighttime sleep," Zee said.
The study will be published March 14 in PNAS.
Heart rate increases in light room, and body can't rest properly
"We showed your heart rate increases when you sleep in a moderately
lit room," said Dr. Daniela Grimaldi, a co-first author and research
assistant professor of neurology at Northwestern. "Even though you are
asleep, your autonomic nervous system is activated. That's bad. Usually,
your heart rate together with other cardiovascular parameters are lower
at night and higher during the day."
========================================================================== There are sympathetic and parasympathetic nervous systems to regulate
our physiology during the day and night. Sympathetic takes charge during
the day and parasympathetic is supposed to at night, when it conveys restoration to the entire body.
How nighttime light during sleep can lead to diabetes and obesity
Investigators found insulin resistance occurred the morning after people
slept in a light room. Insulin resistance is when cells in your muscles,
fat and liver don't respond well to insulin and can't use glucose from
your blood for energy. To make up for it, your pancreas makes more
insulin. Over time, your blood sugar goes up.
An earlier study published in JAMA Internal Medicine looked at a large population of healthy people who had exposure to light during sleep. They
were more overweight and obese, Zee said.
"Now we are showing a mechanism that might be fundamental to explain
why this happens," Zee said. "We show it's affecting your ability to
regulate glucose." The participants in the study weren't aware of the biological changes in their bodies at night.
==========================================================================
"But the brain senses it," Grimaldi said. "It acts like the brain of
somebody whose sleep is light and fragmented. The sleep physiology is
not resting the way it's supposed to." Exposure to artificial light
at night during sleep is common Exposure to artificial light at night
during sleep is common, either from indoor light emitting devices or
from sources outside the home, particularly in large urban areas. A
significant proportion of individuals (up to 40%) sleep with a bedside
lamp on or with a light on in the bedroom and/or keep the television on.
Light and its relationship to health is double edged.
"In addition to sleep, nutrition and exercise, light exposure during
the daytime is an important factor for health, but during the night we
show that even modest intensity of light can impair measures of heart
and endocrine health," Zee said.
The study tested the effect of sleeping with 100 lux (moderate light)
compared to 3 lux (dim light) in participants over a single night. The investigators discovered that moderate light exposure caused the body to
go into a higher alert state. In this state, the heart rate increases as
well as the force with which the heart contracts and the rate of how fast
the blood is conducted to your blood vessels for oxygenated blood flow.
"These findings are important particularly for those living in modern
societies where exposure to indoor and outdoor nighttime light is
increasingly widespread," Zee said.
Zee's top tips for reducing light during sleep (1) Don't turn lights
on. If you need to have a light on (which older adults may want for
safety), make it a dim light that is closer to the floor.
(2) Color is important. Amber or a red/orange light is less stimulating
for the brain. Don't use white or blue light and keep it far away from
the sleeping person.
(3) Blackout shades or eye masks are good if you can't control the outdoor light. Move your bed so the outdoor light isn't shining on your face.
Is my room too light? "If you're able to see things really well, it's
probably too light," Zee said.
Other Northwestern authors are co-first author said co-first author
Ivy Mason, who at the time of the study was post-doctoral fellow at Northwestern and now is a research fellow at Harvard Medical School,
Kathryn Reid, Chloe Warlick, Dr. Roneil Malkani and Dr. Sabra Abbott.
The research was supported, in part, by the National Center for Advancing Translational Sciences grant 8UL1TR000150-05, National Heart, Lung, and
Blood Institute grant R01 HL140580, National Institute of Aging grant P01AG11412, all of the National Institutes of Health, and the American
Heart Association.
========================================================================== Story Source: Materials provided by Northwestern_University. Original
written by Marla Paul.
Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Ivy C. Mason, Daniela Grimaldi, Kathryn J. Reid, Chloe D. Warlick,
Roneil
G. Malkani, Sabra M. Abbott, Phyllis C. Zee. Light exposure during
sleep impairs cardiometabolic function. Proceedings of the National
Academy of Sciences, 2022; 119 (12) DOI: 10.1073/pnas.2113290119 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220314154355.htm
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